Clinch Leatherwood Posted August 28, 2012 Share Posted August 28, 2012 It looks like some sort of MCV moving away as remnants of previously deep convection. Thanks that's what I figured. Looks to me like the storm is about to shed that intense convection to the SE. NHC seems to think it picks up 10 in the next 12 hours and that seems reasonable. Link to comment Share on other sites More sharing options...
Dsnowx53 Posted August 28, 2012 Share Posted August 28, 2012 Issac definitely looks better structurally, it just hasn't seemed to put it all together yet. Issac might still have another 24+ hours over water, given the west trends in the modeling which makes sense given the weak weakness and the strong ridging, so a sigh of relief cannot be had just yet. Link to comment Share on other sites More sharing options...
phil882 Posted August 28, 2012 Share Posted August 28, 2012 Despite that, though, there *was* a dropsonde with 65 70 KT winds at the surface. I guess that isn't enough. Thats the most perplexing thing to me. Meanwhile radar continues to improve as the system slides off to the west Link to comment Share on other sites More sharing options...
RobbTC Posted August 28, 2012 Share Posted August 28, 2012 Not upgrading now gives them the option of doing a full package update at 1pm CT with a new track instead of an intermediate advisory with old track. Link to comment Share on other sites More sharing options...
CandymanColumbusGA Posted August 28, 2012 Share Posted August 28, 2012 Perhaps they're holding off until they see wind data from the buoys and oil rigs sustain hurricane strength. None of them, from the quick glance I've made as I've been in meetings most of the morning, are showing sustained 65 kt winds... That and perhaps they're waiting to see more than one or two dropsondes come back with winds greater than 65 kts... These are all just theories as to why they haven't upgraded Isaac. However, I may have missed a few obs from my cursory glance at recent data... Link to comment Share on other sites More sharing options...
lakeeffectkid383 Posted August 28, 2012 Share Posted August 28, 2012 Interesting insights. Even as I have good confidence in the technical explanation offered by the NHC for the lack of an upgrade, I suspect that it might be better to err on the side of calling storms near hurricane strength (~70 mph maximum sustained winds with at least some evidence of stronger winds via reconnaissance) a hurricane. That would give added emphasis to the public safety message. The precise measurements related to the storm could be left to the end-of-season report. I don't think much would be lost given that such an approach would yield only modest revisions, but it might bolster public responsiveness to the approaching storm. If so, the trade-off would probably be worth it. Anyway, that's just my thought. Agree 100% Link to comment Share on other sites More sharing options...
turtlehurricane Posted August 28, 2012 Share Posted August 28, 2012 Isaac's infrared signature continues to improve with convection deepening near the center. The whole convective pattern is rotating as well so the northern semicircle is becoming more convectively active by the hour. We'll see if it continues but based on Isaac's past I pretty much expect the convective asymmetry to keep propagating cyclonically. http://www.ssec.wisc.../loop_srso.html Link to comment Share on other sites More sharing options...
BeauDodson Posted August 28, 2012 Share Posted August 28, 2012 They have raised the IKE scale to 4.1 for wave/surge Link to comment Share on other sites More sharing options...
David Reimer Posted August 28, 2012 Share Posted August 28, 2012 It will be interesting to see if we see surface winds catch up to the low pressure. Katrina did something similar in the eastern Gulf of Mexico, but obviously on a much more significant scale. Link to comment Share on other sites More sharing options...
phil882 Posted August 28, 2012 Share Posted August 28, 2012 Perhaps they're holding off until they see wind data from the buoys and oil rigs sustain hurricane strength. None of them, from the quick glance I've made as I've been in meetings most of the morning, are showing sustained 65 kt winds... That and perhaps they're waiting to see more than one or two dropsondes come back with winds greater than 65 kts... These are all just theories as to why they haven't upgraded Isaac. However, I may have missed a few obs from my cursory glance at recent data... The whole point of "maximum sustained winds" is just that... It doesn't matter if some spotty surface observations don't report hurricane force winds, as long as there is one area that does. I am wondering why the dropsonde data was not mentioned in the discussion. Link to comment Share on other sites More sharing options...
Bozart Posted August 28, 2012 Share Posted August 28, 2012 As a heavy consumer of products disseminated by our government's weather services, I prefer the scientifically precise approach. I would not appreciate any suspicion the Weather Service is playing me "for effect." I would not like the burden of having to filter for that consideration on my own. Neither would the public, which would in some measure begin to tune out if it came to suspect spin for effect. Link to comment Share on other sites More sharing options...
HurricaneJosh Posted August 28, 2012 Share Posted August 28, 2012 Interesting that the H*WIND surface-wind analysis clearly shows a hurricane, with a large area of 65-kt winds. They're usually lower than operational/best-track. Link to comment Share on other sites More sharing options...
A-L-E-K Posted August 28, 2012 Share Posted August 28, 2012 12z GFS continues with the painfully slow west wobbling prior to landfall...epic rains. Link to comment Share on other sites More sharing options...
turtlehurricane Posted August 28, 2012 Share Posted August 28, 2012 Recon says the center is 14 miles northeast of the old fix, must have something to do with Isaac's center of mass adjusting towards the east and north. Link to comment Share on other sites More sharing options...
Quakertown needs snow Posted August 28, 2012 Share Posted August 28, 2012 radar picking up circulation. it will be interesting to see total rain fall in about 24-48hrs. Link to comment Share on other sites More sharing options...
phil882 Posted August 28, 2012 Share Posted August 28, 2012 Interesting that the H*WIND surface-wind analysis clearly shows a hurricane, with a large area of 65-kt winds. They're usually lower than operational/best-track. H*WIND uses both Dropsonde and Flight level winds, along with a handfull of other data. I use to quality control some of the data back when QUIKSCAT was active. I agree that it usually has a low bias, so this suggests that we have a hurricane. 12z GFS continues with the painfully slow west wobbling prior to landfall...epic rains. The 12z GFS has come in line with the HRRR showing a track just offshore up until 12z tomorrow. In fact the entire center doesn't push fully onshore until tomorrow evening. Link to comment Share on other sites More sharing options...
am19psu Posted August 28, 2012 Share Posted August 28, 2012 Split the NHC policy discussion off into its own thread: Please respond to this topic there and leave this thread to discuss Isaac specifically. Link to comment Share on other sites More sharing options...
battlebrick Posted August 28, 2012 Share Posted August 28, 2012 974 mb extrap Link to comment Share on other sites More sharing options...
David Reimer Posted August 28, 2012 Share Posted August 28, 2012 Estimated pressure 974.1 MB 153600 2808N 08824W 8426 01283 9741 +222 +197 166022 025 021 002 00 Link to comment Share on other sites More sharing options...
SBUWX23 Posted August 28, 2012 Share Posted August 28, 2012 You have to think the dry air that has been a problem the past few days is preventing the hurricane force winds from mixing down to the surface. Link to comment Share on other sites More sharing options...
HurricaneJosh Posted August 28, 2012 Share Posted August 28, 2012 Estimated pressure 974.1 MB 153600 2808N 08824W 8426 01283 9741 +222 +197 166022 025 021 002 00 Amazing that it just keeps dropping, and yet... Link to comment Share on other sites More sharing options...
David Reimer Posted August 28, 2012 Share Posted August 28, 2012 Dropsonde just measured 975 MB pressure with 4 knots at splash. Link to comment Share on other sites More sharing options...
turtlehurricane Posted August 28, 2012 Share Posted August 28, 2012 This has got to be a hurricane now, recon is finding hundreds of miles of hurricane force winds at flight level, with peak flight level winds up to 100 mph. SFMR isn't finding much hurricane force sfc winds but under convection there must be. Isaac now centered 80 miles from the tip of the delta and 165 miles from downtown New Orleans. Winds gusting over tropical storm force across eastern LA with winds sustained near 35 mph. 1.6 ft of surge on the south shore of Lake Pontchartrain, 3.4 ft of surge at Shell Beach, and 2.3 ft of surge at the tip of the delta (where winds are gusting over 60 mph). It's been 1.5 hours since this post, now 3.7 ft of surge at Shell Beach, 2.4 ft at the tip of the delta, and 1.7 ft on the south shore of Lake Pontchartrain in New Orleans. Shell Beach is rising the quickest since it's where all the water is being funneled into. We've passed high tide in the open Gulf and it's about high tide in the coastal marshes, New Orleans high tide isn't for another 6 hours but the tidal amplitude is small anyways, so the tide that really matters is the tide in the coastal marshes/gulf. Low tide in the open gulf is going to be at 6 pm with the next high tide at 8 am... pretty bad timing for Louisiana. Link to comment Share on other sites More sharing options...
PSUBlizzicane2007 Posted August 28, 2012 Share Posted August 28, 2012 154900 2808N 08738W 8425 01393 //// +161 //// 179082 085 064 018 01154930 2808N 08736W 8432 01394 //// +158 //// 179087 092 063 020 01 155000 2808N 08735W 8441 01391 //// +156 //// 181092 094 066 021 01 155030 2807N 08733W 8425 01413 9912 +170 +170 183092 094 064 010 01 155100 2807N 08732W 8431 01414 9916 +180 +180 183091 093 066 007 01 155130 2807N 08730W 8426 01422 9922 +170 +170 183088 092 064 008 01 155200 2807N 08728W 8430 01422 9928 +170 +170 183089 089 062 008 01 155230 2807N 08727W 8430 01425 //// +161 //// 182087 089 063 011 01 155300 2807N 08725W 8428 01433 //// +163 //// 182085 086 063 011 01 155330 2807N 08723W 8436 01428 //// +161 //// 181088 089 060 012 01 155400 2807N 08722W 8432 01440 //// +155 //// 177089 090 059 013 05 Looks like FL winds up to 94 KT now... Link to comment Share on other sites More sharing options...
airmarci Posted August 28, 2012 Share Posted August 28, 2012 12Z GFS doesn't bring Isaac onshore until ~00Z Thursday Link to comment Share on other sites More sharing options...
battlebrick Posted August 28, 2012 Share Posted August 28, 2012 94 kts flight level, 66 kts SFMR they have to upgrade edit: there are multiple readings of 100+ mph at FL Link to comment Share on other sites More sharing options...
N. OF PIKE Posted August 28, 2012 Share Posted August 28, 2012 154830 2808N 08740W 8433 01367 //// +163 //// 179072 078 066 017 01 Link to comment Share on other sites More sharing options...
phil882 Posted August 28, 2012 Share Posted August 28, 2012 Multiple 64+ SMFR low rain contaminated obs in the latest pass... I think its safe to call this a hurricane now. Link to comment Share on other sites More sharing options...
David Reimer Posted August 28, 2012 Share Posted August 28, 2012 AF306 3109A ISAAC HDOB 38 20120828 154430 2808N 08754W 8426 01369 9850 +190 +190 188064 065 047 005 01 154500 2808N 08752W 8425 01375 9855 +190 +190 190063 063 046 004 01 154530 2808N 08750W 8429 01375 9862 +190 +190 191062 064 050 009 01 154600 2808N 08748W 8432 01380 //// +181 //// 188061 062 049 010 01 154630 2808N 08747W 8429 01384 9873 +190 +190 190059 062 047 007 01 154700 2808N 08745W 8436 01383 //// +172 //// 187060 060 051 013 01 154730 2808N 08743W 8433 01389 //// +169 //// 186067 073 062 015 01 154800 2808N 08741W 8429 01395 //// +163 //// 183067 072 063 014 01 154830 2808N 08740W 8433 01367 //// +163 //// 179072 078 066 017 01 154900 2808N 08738W 8425 01393 //// +161 //// 179082 085 064 018 01 154930 2808N 08736W 8432 01394 //// +158 //// 179087 092 063 020 01 155000 2808N 08735W 8441 01391 //// +156 //// 181092 094 066 021 01 155030 2807N 08733W 8425 01413 9912 +170 +170 183092 094 064 010 01 155100 2807N 08732W 8431 01414 9916 +180 +180 183091 093 066 007 01 155130 2807N 08730W 8426 01422 9922 +170 +170 183088 092 064 008 01 155200 2807N 08728W 8430 01422 9928 +170 +170 183089 089 062 008 01 155230 2807N 08727W 8430 01425 //// +161 //// 182087 089 063 011 01 155300 2807N 08725W 8428 01433 //// +163 //// 182085 086 063 011 01 155330 2807N 08723W 8436 01428 //// +161 //// 181088 089 060 012 01 155400 2807N 08722W 8432 01440 //// +155 //// 177089 090 059 013 05 Link to comment Share on other sites More sharing options...
turtlehurricane Posted August 28, 2012 Share Posted August 28, 2012 Looks like FL winds up to 94 KT now... And SFMR over hurricane force finally. Link to comment Share on other sites More sharing options...
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